1. Field of the Invention
This invention relates to a method of reproducing high-speed audio data by a CD-ROM player which is capable of reproduce both audio and digital data.
2. Description of the Prior Art
Hitherto, there has been proposed a compact disc-read only memory(CD-ROM) and a compact disc-interactive(CD-I) as an optical disc capable of recording both digital data such as the data operable in computers, and video data as well as audio data, such as music, voice sound and so on. The CD-ROM is a disc standardized for recording above-mentioned digital data as well as audio data in the audio signal area, yet having compatibility with a compact disc(CD) which basically interactive disc deals with acoustic signals only. On the other hand, the CD-I is an interactive disc defined in the Mode-2 of the CD-ROM, and is a standardized system in which the above-mentioned digital data, video data, audio data and so on are recorded per blocks by a time division multiplex mode.
By the way, it has been a common procedure nowadays to read in the digital data at a twice or four times faster speed than the normal speed in order to meet with the recent increase in requirement for high-speed data processing. However, since it is necessary to reproduce the audio data as a correct sound in case that digital data and audio data are taken in by turns form a single disc, in the conventional CD-ROM player, the audio data has to be reproduced at the same speed as the sampling frequency thereof. Due to this, it has been a problem to require a certain time to switch a rotation speed of the disc whenever the signal to be received from the disc is changed from audio to digital and vice versa, and therefore there has not been much merit in processing digital data at a high speed.
A simple solution to this problem has been to read in the audio signal at the same speed as that for reading the digital data, but has not been effective since the conventional CD-ROM player can not make a faithful reproduction of the audio signal at a high speed due to a change in the reproduction speed.
A scheme for overcoming such problems as described above has been suggested in U.S. Pat. No. 5,420,839, issued to Kiyoshi Tateishi on May 30, 1995, which disclosed a highspeed audio data reproducing technique for making a faithful reproduction of the audio data at a high speed by utilizing a CD-ROM data storage device used to transmit the CD-ROM data as an input buffer of an audio signal processing section. According to the high-speed audio data reproducing technique disclosed in the above U.S. Patent, the CD-ROM data storage device converts a transfer rate of the audio data read from a disc being rotated at a high speed into a transfer rate corresponding to the sampling frequency thereof, thereby making a faithful reproduction of the audio data without a reduction in the rotation speed of disc.
In the technique disclose in the above U.S. Patent, the connected position of the CD-ROM data storage device must be changed from the start stage into the end stage of a signal process path and vice versa in accordance with a type of data read in the disc. To this end, as shown in FIG. 1, it additionally requires an audio buffer controller 10 and two selectors 9 and 11 arranged among a CD-ROM data storage 7, an audio signal processing section 11 and a CD-ROM data processing section 6. Due to the audio buffer controller 10 and the two selectors 9 and 11 added as described above, the signal process path in the CD-ROM player becomes long and complicated, and hence it becomes difficult to make an integration of the CD-ROM player circuit.